Device for threading the points of screw blanks



March 12, 1929. D. 1.. SWENDS EN 1 ,705,319

DEVICE ITOR THREADING THE POINTS OF SCREW BLANKS Filed Jan. '14, 1927 Z; Attorney.

Patented Mar. 12, 1929.

UNITED STAT S PATENT OFFICE.

DAVID LEONARD swnnnsnn, or NonRKorINe, SWEDEN.

DEVICE FOR. THREADING THE'POINTS OF SCREW BLANKSQ Applicationfileli'January 14, 1927 Serial No. 161,071, and in Sweden October 2,1926.

The present invention relates to means for threading the points of blanks for carpenters screws, in which the cutting tool is Y moved first parallel to the axis of rotation of the screw blank and then while threading moved at an angle to the same, and in which after the completion of the threading operation the tool is locked at its point of travel most remote from-the center of the blank,

whereby it can'bereturned :to initial working position without damaging the threaded point of the blank, 2

The object of the presentinvention is to provide an improved arrangement of this kind. This is achieved by mounting the tool or tools on' inclined slides carried by a slide rest which is movable in a direction parallel to the axis of rotation of the screw blank, the arrangement being such that the said slide rest partakes in the initial cutting movement and then abuts against a stop,

whereby during the continuation of the movement theinclined slides are caused by suitable connection to move relatively to the slide rest and thus to move the tool or tools in a direction at an angle tothe axis of rotation of the blank, and that the movement of the tool or tools with respect to the slides rest after the completion-of the threading is stopped and the tool locked in that position so that the return to initial position is effected without harming the out threads.

The tool is locked in the above described position by means of a spring pawl which when the threading of the point is completed engages a stop on the rear of the slide so that the tool is held in the same position on the slide that it holds at the completion of the threading during the return movement to initial working position. When the slide restreaches its initial position, the inclined slide with tool or tools is moved in to working position by mechanism hereinafter-more fully described.

The invention is shown in the accompanying drawing, which illustrates an em bodiment thereof, partly in sidewview and partly in section.

The rod 1 is carried forward by acam or ment through thespring 2 the slide rest 3 which is fixed to a sleeve'loosely mounted on said rod, until the flange 4 at theother endrof said sleeve is stopped against the fixed bearing 5,whereafterthe movement of the rod is transferred through the link '6 to the like and brings with itself in its movethe iuclincdslide 7-,which is movable in the slide rest Hereby the rotating blank-7 is threaded by the tool 7 at the desired angle withrespect 'to-the centre line or axis of the blank -W'hen the tool has passed the blank, the stop lever or pawl 8 is spring pulled mivardly behind the stop 9 on the slide 7; The parts retain this relation durmg the-return motion of rod :l',until the pawl 8 through contact with the angled sur-v face 10 of the bearing 5 is disengaged from f the stop 9 and-sliderest. 3 is stopped vby abutment of a fiange'on the inner end of the aforesaid sleeve w th bearing 5, whereafter the inclined slide 7 during the return motion is brought backto its initial work- .ing position. The purpose of this arrangenecessary to provide means, preferablyv driven from the main drive of the machine, for 'reciprocating the shaft 1,- such as av cam. The bearing 5 can be anchored or fixed in'anyconvenient manner to the bed. plate or other suitable part of the lathe or machine, whilst the slide rest 3 maybe adapted to slide along the bed plate.

Having now particularly described and ascertained'the nature of my said invention and in what manner the same is to be performed, what I claim is r l 1; In a device for threading the points of screw blanks in combination, cutter carrying means, movable parallel to the axis of the blank to be threaded, a cutter 'movably mounted on, said carrying means, means for movmg sald cutter carrying means and sald cutter, as a unit, parallel to the axis of said 7 blank prior to the start of the cutting operation, means for stoppingsaid cutter carry mg means, means formovmg said cutter at an angle outwardly from the axis of said blank during the threading operation, means for lockmg said cutter in a position most remote from the axis of sa d blank, means for returnin said cutter in locked )osition to the beginning of its stroke and means for releasing said cutter locking means at'the end of the 'returnimovement' whereby said.

cutter is replaced in its starting. position.

2. Ina device for threadingthe points of screw blanks, in combinatioma slide rest movable parallel to the axis of the blank to be threaded, an inclined slide mounted on said slide. rest,a cutter mounted on the outer end of said slide, means for moving said slide rest and said cutter, as-a vunit, parallel said flange, a slide rest carried by the outer to the axis of said blank prior to the start of the cuttin 0 Jeration means for sto D in i if) C3 the slide rest, means for moving said cutter through said slide during the cutting operation, whereby it follows an outwardly inclined path, a lug mounted 011 the inner end of said slide, a spring pressed pawl mounted on said slide rest and coacting with said lug to lock said cutter in its outermost position, means for returning the cutter to the beginning of its stroke in locked position, and means for releasing said pawl at the endof the return stroke. V

'3. In a device for threading thepoints of screw blanks, in combination, a reciprocating cutter actuating rod movable parallel flanged sleeve loosely mounted on said rod and journaled in a bearing which coacts withthe flanges ofthe saidsleeve to limit its motion, a flange on the inner end of said rod, a. coiled spring-between said sleeve and endof saidsleeve, an inclined slide mounted 011 said slide rest, a link connecting said slide to the outer end of said rod, acutter fixed to the outer end of said slide, :1 lug on the inner end of said slide, a springaetuated pawl mounted on said slide rest and coacting with said lug'to lock said cutter in its outermost position at the end of-the forward stroke of said rod, and an inclined shoulder on said sleeve bearing eoacting with said pawl torelease said cutter at the end of thereturn stroke of said-rod; r

In testimony whereof Iliave affixed-my signature.

DAVID LEON ARD SWENDSEN. V 

